(CNN) -- More than 48 hours after two mangled bodies appeared hanging by ropes from a pedestrian bridge in a Mexican border city, authorities had yet to identify the victims.

But word of the gruesome crime -- and fears about its apparent target -- spread quickly after the bodies of the man and woman appeared Tuesday morning.

The woman was hogtied and disemboweled. Attackers left her topless, dangling by her feet and hands from a bridge in the border city of Nuevo Laredo. A bloodied man next to her was hanging by his hands, his right shoulder severed so deeply the bone was visible.

Posters found with the bodies contained messages mentioning two blogs and threatening users of social media, demanding they stop reporting drug-related crimes in the city, located across the border from Laredo, Texas.

Mexico's notoriously ruthless drug gangs regularly hang victims from bridges and highway overpasses. And bloggers who specialize in sharing news about trafficking have been threatened in the past. But this could be the first time users of such social networks have been targeted.

By Thursday, no information had been released to the media and no press release had been sent to anybody or posted anywhere. There was no news conference.

CNN tried unsuccessfully to get information about the grisly slayings at the local, state, and federal level. Officials were either unavailable or unwilling to release any information about the killings. Local media reported that the male victim was 25 years old and the female 28, without citing any sources.

It's is not unusual for murder victims to go unidentified in Mexico, especially when it comes to drug-related murders, said Ana Maria Salazar, a security analyst in Mexico City and a former Pentagon official.

"It has to do with the fact that you're dealing with ruthless drug traffickers. When investigators are working a crime scene, they have very limited time to do their work because just by being there, they're putting themselves at risk," Salazar says.

Important evidence that may facilitate a quick identification of a body may go uncollected or mishandled.

In many cases, officials are unwilling to release any information, including victims' identities, because the perpetrators may go after them, their families, or the families of the victims, Salazar said.

"Anybody investigating these cases is at risk of becoming a victim," she said.

Last year in August, two officials in charge of investigating the massacre of 72 Central American migrants in the town of San Fernando, Tamaulipas, were found dead only days after the investigation started.

When it comes to organized crime, several factors may delay identification of victims, said Keynes Garcia Leguizamo, the director of the Acapulco morgue.

Sometimes investigators get badly decomposed bodies of people who are from elsewhere and whose families have ignored their whereabouts for years, he said.

"Tattoos are very important for us as well as specific body features. I'm saying this because earlier this year we had to process body parts that appeared inside four plastic bags and that's how we were able to establish identity," Garcia said.

According to Garcia, many victims are cartel operatives under the age of 30 who frequently move around the country.

On the slayings in Nuevo Laredo, Salazar, the security analyst, said the case has left many unanswered questions.

"Are the cartels that sophisticated that they can track down people who are tweeting anonymously? Are they following these accounts? Do they have a specialized unit following social networks? These murders raise a lot of other questions about how they're operating," she said.